1. Field of the Invention
The present invention relates to an assembly for binding a boot to a gliding member, such as a cross country ski, but which can also be constituted by a gliding member such as a snowboard, roller skates, ice skates, etc.
The invention is related more specifically to a binding assembly in which the boot is attached to the gliding member through its front portion, whereby its rear portion, especially the heel zone, remains free so as to allow for a movement of the foot.
2. Background and Material Information
A binding assembly of the above-mentioned type is especially used in cross country skiing where the movement of the foot is essential, both in the so-called conventional techniques and in the skating step.
The problem is to establish a compromise between two totally conflicting requirements, namely:
a maximum movement of the foot, which is necessary for obtaining a large stride amplitude; and
an optimum control and guidance of the ski that, on the contrary, can only be obtained through a continuous "contact" of the foot with such ski.
This compromise has been obtained, until now, by providing a guiding edge which cooperates with the boot, over the entire length of the latter, and by means of an elastic system provided on the binding at the front of the boot and exerting thereon a return force towards the ski.
Such a system enables an important improvement to the guiding of the ski by the boot since the latter remains engaged, almost constantly, with the guiding edge of the ski itself during the lifting of the heel, as long as the metatarsal zone of the boot remains in support on the ski.
On the contrary, once the entire boot is separated from the upper surface of the ski and therefore escapes from the guiding edge, i.e., when in the position of extreme movement of the boot, the latter almost no longer permits any control of the ski. In addition to this problem, a problem of twisting of the boot sole rises as soon as the foot is raised, a twisting that is also detrimental to a good control of the ski.